1. Field of the Invention
The present invention relates to tissue examination. More particularly, the invention relates to an automated breast palpation device that provides images of palpable findings within breast tissue.
2. Description of the Related Art
Early detection of the formation of tumors or lesions, particularly those caused by cancer, has been a problem for some time, and numerous devices and techniques have been proposed or developed for cancer diagnosis. For example, mammography and physician examination are widely used techniques that have proven to be effective breast cancer diagnosis tools. A number of other technologies have also been proposed for breast cancer diagnosis such as thermography, ultrasound, CAT scanning and light scanning. In most situations, these technologies have proven to be ineffective. MRI is the latest development in breast cancer diagnosis and, as yet, the jury is still out on its ability to separate benign from malignant lesions. The high current cost of the MRI examination and the need for injected contrast media remove it from consideration for cancer screening. Even with continued research into new technologies for breast cancer diagnosis, mammography and physician examinations including breast palpation remain the standard examinations in breast cancer detection.
The preeminence of mammography and physician examinations in breast cancer detection can be seen in the American Cancer Society (ACS) guidelines for breast cancer detection shown in Table 1 below.
ACS Guidelines for Cancer Detection Age Recommendation 20 Breast Self Examination (BSE) monthly 20-40 Breast Physician Examination (PE) every 3 years 40+ Breast Physician Examination (PE) every year 35-40 Initial mammogram 40-49 Mammogram every 1-2 years 50+ Mammogram every year
It can be seen that breast self examination (BSE) and physician examination (PE) are the only recommended detection methods prior to age 35 and except for an initial mammogram, until age 40. Physician examination (PE) additionally accompanies screening mammograms. However, even though a physician examination should accompany a mammogram, there are mammography facilities that do not provide the service. Not only does this necessitate a trip to a second facility, it entails a second appointment and additional cost. As a result, certain women may not undergo a breast physician examination in conjunction with a mammogram.
It is recognized that mammography and physician examination (PE) are synergistic techniques, i.e., a combination of these techniques increases the effectiveness of breast cancer detection. Certain physicians perform a breast physical examination (PE) on each woman receiving a mammogram. It has been observed that some women with initially negative physical findings and suspicious mammograms have some palpable finding on focused breast palpation. Ultrasound and biopsy have proven this relationship. Therefore, it is obvious that a physician examination including breast palpation is an accurate method of breast cancer detection.
However, breast palpation does have certain limitations. The challenge is to differentiate significant palpable findings from the nonsignificant ones that are little different. In many patients, the findings are not conclusive and the breast examiner has difficulty in interpreting what his fingers feel in the breast. The question that must be answered is "is the nodularity which he feels within the limits of the normal physiologic variation in breast structure or does it represent a dominant tumor due to inflammatory or neoplastic disease?" It is apparent that a measurable difference in resistance may exist between significant and nonsignificant findings. Unfortunately, the human fingertip may not be sensitive enough to measure the difference. In fact, it is believed that palpation is not able to detect tumors of less than about one centimeter in size.
Breast palpation also has data acquisition and analysis limitations not present in other breast cancer detection techniques. For instance, mammography provides the physician with a visual image that can be reviewed and compared and saved for future reference. This enables mammography to demonstrate a developing mass using serial studies. In contrast, manual breast palpation by its nature cannot provide a visual image for review and future reference.
In order to increase the sensitivity of palpation and allow for data acquisition and analysis, a number of devices for mimicking breast palpation to detect tumors have been developed. For example, U.S. Pat. No. 4,250,894 discloses an instrument for breast palpation that use a plurality of electret strips which are pressed into the body being examined by a pressure member which applies a stress to the tissue beneath the electret strips. A signal processor interrogates the output voltage of each of the strips and the output is displayed to produce a display characteristic that shows the presence of an inclusion in the breast tissue being examined. U.S. Pat. No. 5,833,634 discloses a tissue examination device that includes: (1) a transducer element for generating a signal in response to force imposed on the transducer element in accordance with the varying properties of the underlying tissue structure and (2) circuitry for detecting a variation in the signal as an indication of a localized area of stiffer tissue within the tissue. U.S. Pat. Nos. 5,524,636 & 5,860,934 disclose a device including a pressure sensor array, a data acquisition circuit and a microprocessor mounted in a hand held pad. Detection of any lumps in the breast is achieved by analyzing the features of the pressure pattern when the pad is pressed to the breast.
While these devices may be valuable tools for breast cancer detection, they do have certain limitations. Specifically, these devices are hand held and therefore, cannot be moved over the breast in a repeatable pattern that allows for accurate serial studies.
Therefore, there is a continuing need for improved breast palpation methods. Specifically, there is a need for an automated breast palpation machine that: (1) provides an image of palpable findings that can be reviewed; (2) provides an image of palpable findings that will be available to the mammographer at the time of interpretation; (3) includes repetitive examination that provides a means of detecting a developing locus of increased resistance before a recognizable palpable mass has appeared; and (4) provides the opportunity to detect significant palpable resistance that is presently below the threshold of clinical recognition.
It is therefore an object of the present invention to provide an automated breast palpation machine that generates an image that can be reviewed and compared to other images.
It is still another object of the present invention to provide an automated breast palpation machine that can recognize significant palpable findings currently below the clinical threshold of manual breast palpation.
It is yet another object of the present invention to provide an automated breast palpation machine that can demonstrate a developing mass on serial studies.
It is a further object of the present invention to provide an automated breast palpation machine that can insure that breast palpation is used in conjunction with screening mammograms.